Surveillance, detection, and tracking of multiple high-speed objects, particularly bullets, mortars, small rockets, and artillery shells, can help military forces immediately locate sources of enemy fire and trigger countermeasures, thereby reducing combat casualties.
The traditional techniques for detection and tracing of fast moving objects are different kinds of radar but unfortunately, traditional radar has inherently low resolution for such small objects. Worse yet, radar cannot scan 360° of azimuth with a high enough frequency (times per second) for timely bullet detection.
Fast moving projectiles rapidly heat up by several hundred degrees Kelvin, thereby radiating in the Mid-Infrared (MWIR) region, where electro-optical resolution is far superior, even to microwave radars. An MWIR system of the prior art was recently developed by Trex Enterprise Corp and is described in Ref. [1]. This technique comprises a high-resolution, “roving fovea” MWIR telescope for projectile tracking and a coordinated pulsed-laser radar (lidar) for distance determination. The rapidly slewing “roving fovea” method is quite fast by mechanical standards, but it still takes 200 msec for one scan of a field of regard of only 36° square and, therefore, five seconds are required for a full hemisphere. This means that bullets will not be detected and tracked to any useful extent. Moreover, the use of lidar on a precise targeting platform results in a system that is too bulky and expensive to purchase and not useful for tracking anything smaller than rockets and artillery shells.
One object of the present invention is to make possible a compact, cost-effective passive electro-optical tracker of multiple high-speed objects in a combat environment. The Passive Electro-Optical Munitions Tracker (PET) described in this specification can assist in providing pinpoint 3D information in real time to back-track projectiles to their source of fire.